Infraspinatus

Muscle parts

None

Latin name

Musculus infraspinatus

Latin muscle parts

None

Group

Shoulder joint muscle – rotator cuff

Etymology

The English name for this muscle is the muscle below the spine. The term infra is Latin meaning “below or underneath” and spinatus comes from the Latin spina meaning “thorn.” Spina was originally used to describe any thorn-like or pointed projection, like the spinous processes of the vertebrae. This term was then transferred to the dorsal ridge formed by the individual spinous projections of the vertebrae. On the scapula it forms a dorsal ridge of bone.

Origin

Medial aspect of the infraspinous fossa of the scapula and the tendinous septa of the fossa.

Insertion

Middle aspect of the greater tubercle of the humerus.

Action

Lateral rotation of the humerus – it acts with the teres minor and the posterior fibers of the deltoid to produce this movement.Stabilizes the shoulder joint – as one of the rotator cuff muscles, the infraspinatus plays a critical role in stabilizing the shallow shoulder joint. It plays an important role in holding the humeral head down during the initial part of abduction.